1. Technical Field
The invention relates to a sensor for optically measuring a range, a position and/or a profile of an object that is to be measured, the measured object emitting electromagnetic radiation due to the temperature of the object to be measured, and the sensor having a light source for illuminating the surface of the measured object and a detector for detecting the illuminating light reflected at the object to be measured. Furthermore, the invention relates to a corresponding method.
2. Description of Related Art
Optical sensors for measuring a range, a position and/or a profile of an object that is to be measured have been known for a long time from the field. A light beam—typically a laser beam—is emitted as an illuminating light beam and is reflected at an object that is to be measured. That part of the illuminating light beam that is reflected back to the sensor is measured by a detector. The measurements allow conclusions to be drawn about the position and/or the range of the measured object relative to the sensor. In the case of a point-shaped illumination of the object to be measured, a profile of the measured object can be determined by moving the sensor, guiding the light beam and/or moving the object to be measured. In the case of non-point-shaped (for example, line- or grid-shaped) illumination patterns, a profile can be determined even without movement. A simple profile measurement can be performed with some types of optical sensors without a range measurement.
A very popular type of optical range sensor is the triangulation sensor, where the light source, the measurement point illuminated on the object to be measured, and the detector form a triangle. The distance of the measured object from the sensor is determined based on the knowledge of the geometry of the triangulation sensor and the position of the light spot on the detector.
Essential for optical measurements is the condition that a sufficient intensity of the light emitted by the sensor be reflected back to the detector and that the reflected light generate a sufficiently bright measurement spot, stripe or pattern on the detector.
Optical measurement methods pose a particular problem, especially if measurements on self-luminous bodies are to be performed. One of the most important cases of self-luminous objects to be measured are hot objects. At temperatures exceeding 700° C., the bodies emit not insignificant radiation in the infrared range. As the temperature rises, the fraction of electromagnetic radiation in the visible optical range increases. If measurements on self-luminous bodies are to be performed, then the intensity of the illuminating light has to be increased for the optical sensor arrays known from the prior art, or one will have to resort to other sensor technologies, like capacitive or inductive sensors. However, one does not always want to or one cannot always dispense with the advantages of optical sensors. For example, optical sensors have, compared to other contactless sensing sensors, relatively large measurement ranges and at the same time good resolutions. Furthermore, reliable measurements can be performed on a plurality of different conductive or non-conductive materials. However, the consequence of increasing the intensity of the illuminating light is, on the one hand, an increase in the energy consumption of the sensor and, on the other hand, there is the need to observe the legally prescribed power output limit values when using lasers as the light sources, so that the power output cannot be increased in any arbitrary way.
Therefore, the object of the present invention is to configure and further develop a system and a method intended for optically measuring a range, a position and/or a profile and conforming with the type described in the introductory part in such a way that measurements can also be performed on measured objects that emit electromagnetic radiation.